Pedagogical development and technical research in the area of geothermal power production

Sammanfattning: This work describes the types of power plants used for geothermal power generation in the world; the dry steam power plant, the flash steam power plant and the binary cycle power plant. The objective of the MSc work was the development of learning content on the subject of geothermal power generation for the CompEdu platform in the energy department at KTH. The power plants are described from a system perspective followed by an explanation of the operation of major components. Examples and calculations are given with the aim of illustrating which parameters are most important to the operation of each plant from a performance perspective. An important point is that the report does not go into detail for auxiliary components such as piping and valves. These components are essential from the point of view of fluid handling, however are less important in terms of understanding the mode of operation of the power plant. The power plants must consider the fact that geothermal fluid is corrosive and contains non-condensable gases. The choice of the type of geothermal power plant depends on the temperature and state of the geothermal fluid being utilised (liquid or vapour dominated). The research shows that each power plant has its own significant optimisation criteria, to summarise these: the dry steam power plant uses the selected wellhead pressure for extraction of geothermal fluid to optimise power output, the flash steam power plant uses the operating conditions in the steam separator to optimise power output and the binary cycle uses the required heat exchanger area per unit of power generated to select the optimal working fluid for power generation. Finally, innovative alternatives for power generation from geothermal resources that are on the horizon are introduced.